Becoming a living "blood bag" in Mad Max: Fury Road likely would have killed the title character. The original Mad Max seemingly roared out of nowhere in 1979 to become a major cult hit thanks to its unique vision of the future, intense car chases, and Mel Gibson's star-making performance. Gibson and director George Miller returned for 1981's Mad Max 2: The Road Warrior, where Max reluctantly helps a band of survivors against marauding villains. The sequel greatly up the scale and scope and is still considered one of the best post-apocalyptic movies ever made.
Venom). This entry was acclaimed for its action, production design, and performances, especially Charlize Theron's instantly iconic Imperator Furiosa.
While the franchise isn't striving for total realism, the fact George Miller used to be a doctor gives it a somewhat grounded feel. In X-Men: First Class).
When the War Boys are rallied to give chase to Furiosa, the weak Nux insists Max is strapped to the front of his car so he can still provide blood during the chase. This universal donor situation also comes in handy during Mad Max: Fury Road's ending, where Max willingly gives his blood to save Furiosa. That said, realistically there's a very good chance the amount of blood he gave to Nux would have straight up killed him, or at the very least prevented all the action he's seen performing.
A paper from the University Of Leicester (via Nerdist) broke down Max's use as a blood bag, including the amount of time he's hooked up and the approximate amount of blood taken. Given that he appears to be constantly giving blood for at least 20 minutes of screentime, it's estimated he would have given around 3.31 liters of blood to Nux - meaning he lost 60% of his blood. To put that number in perspective, if a person loses over 40% of their blood supply, this is almost certainly fatal.
So basically, Max would have ed out and died after he ed the 40% mark. Of course, Mad Max: Fury Road isn't a documentary and for action sequences that good, a little creative license is forgivable. Hopefully, Max had a hearty meal after it was finished though.
